Quality-of-information aware transmission policies with time-varying links

We consider Quality-of-Information (QoI) aware transmission policies in the presence of time-varying links in a mobile ad hoc network. QoI, tailored for military tactical networks, is defined by a set of attributes relevant to the application. Time-varying nature of links in practical networks leads to uncertainty in evaluating QoI utility to be delivered to end users. This delivered-QoI utility is a function of both attributes provided by the source input, as a result of observing certain events, and the channel induced attributes that impact the QoI obtained at the destination. The goal of this paper is to attain the maximum QoI output utility, termed as Operational Information Content Capacity (OICC) of a network. First, for a single link, we demonstrate that the optimal decision structure for transmission is threshold-based. Next, we consider multihop relay networks. For the basic model of a two-hop relay network, we propose transmission scheduling and link activation schemes based on approximate dynamic programming methods. Furthermore, we exploit time-variations of links by opportunistic scheduling by employing buffers at the relay node. We demonstrate that significant gains in QoI output utility are gained by opportunistic scheduling algorithms.